Space Vector PWM Scheme Research Articles

A Novel Volt-Second Self-Balancing SVPWM Scheme to Eliminate Steady-State DC Bias for a Three-Phase Isolated AC–DC Matrix Converter

For a three-phase isolated ac-dc matrix converter, the slight volt-second imbalance caused by variable input voltage is an inherent defect and has been neglected in most PWM schemes. The analysis in this paper shows that the imbalance lies in a single direction during the entire input cycle, and it might generate a large dc bias to severely decrease the efficiency of the steady-state operation. Therefore, the imbalance phenomenon is first investigated, and the generation mechanism of the steady-state dc bias is derived in detail. To eliminate such a dc bias, a novel transformer primary-side voltage pulse is originally defined. Based on the special crisscrossing operation mode with the above pulse, a simple but effective four-segment space vector PWM (4S-SVPWM) scheme is proposed. Compared with the conventional more-segment SVPWM schemes, the novel 4S-SVPWM scheme can achieve volt-second self-balancing without auxiliary methods, as well as a 1/2 reduction in the common-mode voltage (CMV) peak value and a 1/3 reduction in the switching actions. The overall efficiency and power density of the converter are greatly improved. Finally, an experimental prototype is built to validate the correctness and effectiveness of the novel scheme.

Dodecagonal Voltage Space Vector Based PWM Techniques for Switching Loss Reduction in a Dual Inverter Fed Induction Motor Drive

The dodecagonal space vector generation scheme eliminates the most dominant lower order harmonics fifth and seventh for the entire modulation range, thereby improving the quality of the output waveform and eliminates the sixth harmonic torque pulsations. By considering this advantage, a group of dodecagonal space vector pulsewidth modulation (PWM) techniques is proposed in this article. These techniques improve the harmonic profile of the output waveform further at higher modulation indices compared to conventional dodecagonal space vector PWM. In this article, a generalized closed-form expression for harmonic distortion of various dodecagonal space vector PWM schemes is derived and the analytical results are compared. The proposed PWM techniques are simulated in MATLAB/Simulink environment and validated experimentally on a laboratory prototype. Also, a detailed switching loss analysis for various dodecagonal space vector PWM schemes are obtained and it is shown that the proposed PWM techniques yield lower inverter switching power losses than the conventional scheme throughout the power factor range.

Comparison study between seven-level SVPWM and two-level SVPWM strategy in direct vector control of a DFIG-based wind energy conversion systems

<span>In this paper, we present a comparative study between two-level space vector pulse width modulation (SVPWM) and seven-level SVPWM strategy in direct vector control (DVC) of a doubly fed induction generator (DFIG) based wind energy conversion systems (WECSs). The feasibility and effectiveness of the two strategies are demonstrated by simulation results. The obtained results showed that, the proposed DVC strategy with Seven-level SVPWM technique have stator and rotor current with low harmonic distortion and low active and reactive powers ripples than two-level SVPWM strategy.</span>

ANFIS-sliding mode control of a DFIG supplied by a two-level SVPWM technique for wind energy conversion system

A modified adaptive neuro-fuzzy inference system sliding mode control (ANFIS-SMC) by using two-level space vector pulse width modulation (SVPWM) for doubly fed induction generator (DFIG) is proposed in this article. ANFIS-SMC with SVPWM strategy improves the basic SMC performances, which features low stator active and reactive power and also minimize the total distortion harmonic (THD) of stator current. The computer simulation results, in Matlab, demonstrate the effectiveness of the proposed control strategy which improves the performance of the DFIG.

Novel space vector PWM technology with lower common‐mode voltage for dual three‐phase PMSM

Pulse width modulation (PWM) converters generate switching common-mode voltages (CMV) across the load terminals. These voltages cause common mode currents, leading to bearing failure in motor loads and electromagnetic interference problems. This study proposes a novel space vector PWM strategy to reduce the CMV in the dual three-phase permanent magnet synchronous motor (PMSM) driven by two-level six-phase inverter. The novel space vector PWM algorithm discards the use of zero vectors. Firstly, the two largest voltage vectors of each sector are selected as main vectors to synthesise reference vector. Then, three groups voltage vector, which are opposite to the main vectors, have been selected as auxiliary vectors. Appropriate auxiliary vector selected is based on the length of zero voltage vector working time. Next, zero vector working time is distributed to the main and selected auxiliary vectors based on voltage-second principle. In addition, CMV and the harmonic component in z1z2 subspace of the proposed space vector PWM are analysed in detail. Finally, the expected CMV reduction to one-sixth of DC voltage and change rate of CMV in each cycle promised by the proposed novel space vector PWM are demonstrated with simulation and experimental results.

Two Novel Open-End Winding Multilevel Unidirectional Six-Phase Rectifiers With Reduced Switch Count

In this article, two new unidirectional multilevel six-phase power rectifier topologies are proposed and investigated. Such topologies may be applied to ac–dc systems such as wind energy conversions systems, aerospace generator drives, telecommunications or any other application where regenerative operation is either not required or prohibited. The first topology is composed of two three-level neutral-point-clamped (NPC) converters connected to the open-end windings of a six-phase permanent magnet synchronous generator, and a three-phase noncontrolled diode bridge converter. The second topology is composed of three modified NPC converters with the substitution of two controlled switches by diodes in each leg. The use of a noncontrolled converter with diodes aims to reduce the controlled switches count, the system complexity, and the costs. However, it makes both systems nonreversible. The system models, operating principles, the space vector pulsewidth modulation strategies, the dc-links balance, and the control system to ensure the elimination of the zero-crossover distortion caused by the use of the diodes are presented. Due to the high number of levels generated, the systems are suitable for high power applications with voltage and current ratings restrictions. A study concerning harmonic distortion and semiconductor losses for both systems is performed, in order to be compared with a standard configuration. The feasibility of the system is demonstrated by simulation and experimental results.

ANFIS based multi-sector space vector PWM scheme for sensorless BLDC motor drive

This paper presents a design and development of Multi Sector Space Vector Pulse Width Modulation scheme (MS-SVPWM) for the speed control of brushless direct current (BLDC) motor drive. This control scheme is developed to enhance the performance of BLDC under wide range of speed and load variation. The hardware prototype is developed for 400 W, 30 V, 3000 rpm BLDC motor. The drive consists of uncontrolled rectifier unit for providing DC source to inverterunit. The proposed drive control has been done by implementing MS-SVPWM scheme using ANFIS control. The main function of ANFIS controller is to select the suitable sector for the drive and also predict the mismatching pulses by comparing conventional SVPWM and MS-SVPWM switching patterns. This new switching control technique helps to reduce switching losses of inverter and also improves an efficiency of BLDC system. This MS-SVPWM reduces the DC voltage ripple; Total Harmonic Distortion (THD) and torque ripple to the standard level. To verify and validate the practicality of the proposed system, the simulation is first performed using MATLAB Simulink tool. The hardware system is developed for the MS-SVPWM using DSPIC30F4011controller, the simulation and experimental results are presented.

SVPWM control strategy for a three phase five level dual inverter fed open-end winding induction motor

A Space Vector Pulse Width Modulation (SVPWM) control strategy is proposed for a three phase five level dual inverter fed open-end winding induction motor. This system includes 2 three level Neutral Point Clamped (NPC) inverters, which is supplied by two isolated dc power supplies. The conventional SVPWM has more complexity in reference vector identification and switching time calculation. The reference vector for proposed five level SVPWM scheme is tracked using three level voltage vector and offset voltage, where 5-level hexagonal region is divided into seven 3-level hexagonal regions. The proposed SVPWM leads to reduce the complexity in switching time calculation, Total Harmonic Distortion (THD) reduction, Minimization of Common Mode Voltage (CMV) and low voltage stresses across the switching devices. Also this system estimate the phase current of the five level dual inverter fed open-end winding induction motor. The results obtained using simulation and hardware are compared and verified using Digital Signal Processor.

Study of interleaved PWM strategies applied to two back-to-back three-phase full bridges

The aim of this study is to evaluate the impact of interleaved PWM strategies on the RMS current flowing through the DC link capacitor associated to two back-to-back three-phase Full Bridges (FB). Indeed, this value is usually the key-parameter for the sizing of this (or these) component(s), far above the capacitance, especially for aluminum electrolytic capacitors. Interleaving technique is applied on two different strategies: Unified Double Carrier PWM (dedicated to reduction of the RMS current for a single FB) and a classical (single carrier) space-vector PWM strategy.

Investigation of SPWM and SVPWM VSI for Induction Motor Drive

This paper investigates the different modulation techniques of voltage source inverter (VSI) for induction motor drive concerning the harmonic distortion. Two types of PWM strategies are analyzed under various operating conditions regarding total harmonic distortion. Both sinusoidal PWM and space vector PWM strategies have been analyzed. THD has a suitable value that reduces the torque ripple. since the high switching frequency provides high ripple. The system is simulated by using Matlab.

Design of New SVPWM Mechanism for Three-Level NPC ZSI via Line-Voltage Coordinate System

In this article, a novel space-vector pulsewidth modulation (SVPWM) mechanism is proposed for a three-level neutral-point clamped (NPC) Z-source inverter (ZSI) via the line-voltage coordinate system. In order to solve the problems of the adjustment of the complicated operational region and the complex computation of lookup tables in conventional methods, the newly designed SVPWM mechanism is developed from the basis of the vector synthesis. With this mechanism, switching vectors required to synthesize the reference vector can be easily identified, and the corresponding duty ratios can be directly obtained. According to the volt–second balanced principle and three operational modes of the three-level NPC ZSI, the up shoot-through status is inserted into the left side of the intersection point of the maximum phase modulation signal and the carrier wave signal. On the other hand, the down shoot-through status is inserted into the right side of the intersection point of the minimum phase modulation signal and the carrier wave signal. The effectiveness of the proposed SVPWM mechanism is verified by numerical simulations and experimental results. The salient features of the proposed SVPWM method are easiness in digital implementation, less computation time, and better power quality in comparison with traditional SVPWM schemes.

Performance Comparison of Five-Phase Three-Level NPC to Five-Phase Two-Level VSI

A multiphase multilevel voltage source inverter (VSI) offers excellent advantages over the traditional three-phase counterparts. Low-order harmonic components with reduced switching losses, lower common-mode voltage (CMV), and the optimum use of dc-link voltage constitute the critical performance indicators for high-efficiency VSI evaluation. Various approaches for carrier-based pulsewidth modulation (CPWM) generation are available in the literature along with space vector pulsewidth modulation (SVPWM) techniques. Comparative analysis shows that the majority of SVPWM strategies have enormous potential than CPWM to achieve the aforementioned performance indices. The main objective of this article is to provide a common platform for the selection of available five-phase VSIs for various industrial applications. For this, a comparative study is carried out to examine in various aspects like CMV, voltage and current total harmonic distortion (THD), switching, conduction losses, and efficiency under the steady-state and dynamic loading conditions over a wide range of the modulation index. It is observed that the five-phase three-level neutral-point-clamped (NPC) VSI has better performance than the five-phase two-level VSI. Experimental results are provided to verify the performance indices of both topologies at steady-state and dynamic conditions.

Quasi-Two-Stage Multifunctional Photovoltaic Inverter With Power Quality Control and Enhanced Conversion Efficiency

A novel quasi-two-stage multifunctional inverter (QMFI) for photovoltaic (PV) applications is proposed in this article. With the help of the quasi-two-stage architecture, part of active power can be directly transferred from PV arrays to the grid or load within a single power conversion stage and hence improve the efficiency. In addition to active power transfer, both the realization of maximum power point tracking (MPPT) and compensation of nonactive current (i.e., reactive, harmonic, or unbalanced current) of the QMFI are considered. A mathematical model of the QMFI is presented to guide the control parameter design. Meanwhile, an analysis model based on the rotating frame is proposed to derive the space vector pulsewidth modulation strategy of the QMFI, and also, offer straightforward insight into the influence of nonactive current compensation on quasi-two-stage active power flow. Compared with traditional solutions, the QMFI can realize active power delivery with higher efficiency and also keep functions of achieving MPPT and enhancing power quality. The feasibility and effectiveness of the proposed solution are verified with a 3-kVA prototype.

Comparison study between SVPWM and FSVPWM strategy in fuzzy second order sliding mode control of a DFIG-based wind turbine

AbstractIn this work, we present a new fuzzy second-order sliding mode controller (FSOSMC) for wind power transformation system based on a doubly-fed induction generator (DFIG) using intelligent space vector pulse width modulation (SVPWM). The proposed command strategy combines a fuzzy logic and a second order sliding mode control (SOSMC) for the DFIG command. This strategy presents attractive features such as chattering-free, compared to the conventional first and second order sliding mode techniques. The use of this method provides very satisfactory performance for the DFIG command. The effectiveness of this command strategy is proven through the simulation results.

Improved Synchronized Space Vector PWM Strategy for Three-Level Inverter at Low Modulation Index

Aimed at reducing the switching loss and common-mode voltage amplitude of high-power medium-voltage three-level inverter under low modulation index conditions, an improved synchronous space vector PWM strategy is proposed in this paper. The switching times in each fundamental period are reduced by the re-division of small regions and the full use of the redundant switching state. The sum of switching algebra is introduced as an evaluation index and the switching state with the minimum value of the sum of switching algebra are adopted. Then, the common mode voltage amplitude is reduced. The theoretical analysis and experimental results show that the improved modulation strategy proposed in this paper can effectively reduce the switching loss and common-mode voltage amplitude of the inverter under the condition of the low modulation index. Moreover, the neutral-point voltage ripple is also reduced simultaneously.

Modulation and Voltage Balancing of a Five-Level Series-Connected Multilevel Inverter With Reduced Isolated Direct Current Sources

The series connection of low-power modules is an alternative solution to realize a multilevel inverter. Unlike a cascade connection, the series connection approach significantly reduces the number of isolated dc sources, thereby the design complexity, cabling of the transformer, and overall system cost become low. In this article, the operation of the series-connected multilevel inverter is presented for a five-level operation, and it is realized by using two three-level half-bridge diode clamp converter modules per phase. Hence, each phase of the series-connected multilevel inverter requires a single isolated dc source. In the series-connected multilevel inverter, the net dc-bus voltage will be equally distributed between four dc-bus capacitors. Therefore, the converter generates a multilevel voltage waveform with uniform steps and ensures equal voltage stress on the semiconductor devices. To achieve these objectives, a space vector pulsewidth modulation scheme with an additional voltage balancing approach is employed. The feasibility of series-connected multilevel inverter is validated through simulations and a scaled-down laboratory prototype under steady-state and transient conditions.

Reactive Power Based MRAS for Speed Estimation of Solar Fed Induction Motor With Improved Feedback Linearization for Water Pumping

This article presents an efficient method for control of a solar water pumping system consisting of an induction motor drive (IMD) with a model reference adaptive system (MRAS) based adaptive mechanism of speed estimation. An improved perturb and observe control technique is implemented to achieve maximum power point tracking. The gating signals are produced by utilizing a space vector pulsewidth modulation scheme for a three-phase inverter. An improved third order integrator (ITOI) is proposed for adaptation of flux for improvement in the performance of the drive. The MRAS is used for estimation of slip speed and synchronous speed two estimated speed signals are used to generate the motor speed. The proposed control methodology with the MRAS-based reactive power technique for the estimation of speed has improved the system stability for a wide range of drive speed. This system with a single-stage photovoltaic (PV) topology and switching logic obtained from space vector modulation operating three-phase voltage source inverter fed IMD with a pump as a load is designed and implemented in MATLAB/Simulink. The suitability of the developed system is validated through experimentation in the laboratory.

Extension of Space-Vector-Signal-Injection-Based MTPA Control Into SVPWM Fault-Tolerant Operation for Five-Phase IPMSM

This article presents a new fault-tolerant drive for a five-phase interior permanent magnet synchronous machine (IPMSM) to achieve the maximum torque per ampere (MTPA) operation under open-circuit faults. In the postfault space vector pulsewidth modulation strategy, the voltage vectors are reconstructed by the reduced-order transformation matrix, which is derived from the optimal reference fault-tolerant currents under single-phase and double-phase fault. The z subspace is particularly controlled to reduce the total harmonic distortions of current under single-phase fault, and the distributions of space voltage vectors are established to realize the fault-tolerant operation under double-phase fault. Meanwhile, the high-frequency signal is injected into the space vector under fault condition inherently to detect the MTPA points. Therefore, this method is parameter independent in the tracking of the MTPA point under postfault operation. Besides, the proposed method can effectively reduce the amplitudes of the fault-tolerant currents and improve the torque and efficiency performances compared with $i_{d}= 0$ fault-tolerant control. Finally, on an IPMSM prototype drive system, the effectiveness of the proposed method is verified by the experiment.

A Simplified 3-D NLM-Based SVPWM Technique With Voltage-Balancing Capability for 3LNPC Cascaded Multilevel Converter

The nearest level modulation (NLM)-based space vector pulsewidth modulation (SVPWM) algorithms have attracted a great deal of interest since they can provide various degrees of freedom, i.e., optimized switching sequences and adjustable duty cycles. This article proposes a simplified three-dimensional (3-D) NLM-based SVPWM algorithm in a 3-D coordinate system. Compared with the generalized two-dimensional (2-D) NLM-based SVPWM schemes, the proposed method not only provides identical degrees of freedom to optimize switching patterns and obtain adjustable duty cycles, but also presents better digital implementation and lower hardware occupancy to achieve the real-time PWM generation. In addition, based on the NLM-based principle, a method of addressing the issue of unbalanced voltages in a three-phase 3-level neutral point clamped cascaded multilevel converter (3LNPC-CMC) is introduced. The presented method possesses the optimized voltage-balancing capacity and equalizes the unbalanced inner cell and mutual cell voltages in the 3LNPC-CMC with minimum number switching transition. Finally, the whole proposed process is verified by simulation and experimental results.

Carrier-Based PWM Equivalent to Multilevel Multiphase Space Vector PWM Techniques

The space vector pulsewidth modulation (SVPWM) techniques enhance the performance of multilevel multiphase inverters. With multilevel (three-phase) inverters and with (two-level) multiphase inverters, it is widely accepted that the typical SVPWM strategies have an equivalent carrier-based pulsewidth modulation (CBPWM) counterpart, which produces identical results. However, the conclusions reached in the articles that show these cannot be applied, nor even extended, to SVPWM techniques with more than two levels and three phases. This article shows that the most widely accepted multilevel multiphase SVPWM techniques have a fully equivalent CBPWM counterpart, which consists of a phase disposition pulsewidth modulation with an appropriate zero-sequence injection scheme. Closed-form expressions to calculate the zero sequences are provided. The proposed modulation techniques are simulated and then implemented in a field-programmable gate array, showing that the equivalent CBPWM techniques produce identical results as the original SVPWM ones, but with a significant reduction of hardware requirements. The proposed methodology can be generalized to other multilevel multiphase SVPWM techniques.